koj, daij, prog, wisdom, gg5

let's go with the esp note.
also, to me an elastic band is something extremely different (= a rubber band) and all of my waeis include jockstrap (though eij gives that specifically as 局部サポーター)

@@ -13 +13,3 @@
-<gloss>supporter (e.g. elastic band)</gloss>
+<gloss>supporter (e.g. wrist supporter)</gloss>
+<gloss>athletic supporter</gloss>
+<gloss>jockstrap</gloss>
@@ -17 +19 @@
-<gloss>supporter</gloss>
+<gloss>supporter (esp. of soccer)</gloss>
@@ -20,5 +21,0 @@
-<sense>
-<pos>&n;</pos>
-<gloss>football supporter</gloss>
-<gloss>soccer supporter</gloss>
-</sense>

daijs doesn't split but mentions football with a "特に": 
"２ 支持者。後援者。特に、サッカーで、特定チームの熱狂的ファン。"
daijr splits: "②支持者。支援者。"
サッカーなどで，ある特定チームを熱烈に応援する人。ファン。"
sports yogo ga wakaru jiten of course only has sports-
related glosses but specifically mentions its people who 
cheer for football teams: 
③サッカーで、勝利を望んで応援する、特定チームのファン。

daijr splits, and daijs has an "esp."
I could go either way (split or "esp." note)

@@ -13 +13 @@
-<gloss>supporter (e.g. elastic band, jockstrap)</gloss>
+<gloss>supporter (e.g. elastic band)</gloss>

what makes sense 2 any different from sense 3?

daij, sports yougo ga wakaru jiten

"regular (guest) on a TV program" is not in daij, no 
evidence on google images

@@ -13 +13 @@
-<gloss>supporter</gloss>
+<gloss>supporter (e.g. elastic band, jockstrap)</gloss>
@@ -17 +17,7 @@
-<gloss>regular (guest) on a TV program</gloss>
+<gloss>supporter</gloss>
+<gloss>backer</gloss>
+</sense>
+<sense>
+<pos>&n;</pos>
+<gloss>football supporter</gloss>
+<gloss>soccer supporter</gloss>