Service on front of the platform (4)
I believe the answer is:
raft
'platform' is the definition.
(I have seen 'Buoyant platform' mean 'raft' so perhaps 'platform' could also mean 'raft')
'service on front of the' is the wordplay.
'service' becomes 'raf'.
'on' is a charade indicator (letters next to each other).
'front of' indicates taking the first letters.
The first letter of 'the' is 't'.
'raf'+'t'='RAFT'
(Other definitions for raft that I've seen before include "Travel on river, in a way" , "River transport" , "host" , "Floating log structure; large amount" , "great deal" .)