Popular supporter having shot foot soldiers (8)
I believe the answer is:
infantry
'foot soldiers' is the definition.
(I've seen this before)
'popular supporter having shot' is the wordplay.
'popular' becomes 'in' ('in' can mean trendy).
'supporter' becomes 'fan' (fan is a kind of supporter).
'having' means one lot of letters go next to another.
'shot' becomes 'try' (both can mean an attempt).
'in'+'fan'+'try'='INFANTRY'
(Other definitions for infantry that I've seen before include "part of the army" , "Foot-soldiers" , "Men fighting" , "Unmounted fighters" , "Troops" .)