Something afoot for the coach (7)
I believe the answer is:
'coach' is the definition.
(as in a sports coach)
'something afoot for the' is the wordplay.
I cannot quite understand how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is present in the answer.
The remaining letters 'rainer' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for trainer that I've seen before include "Shoe; educator" , "Footwear singularly" , "Coach - one of a pair of shoes?" , "Person in charge of stable" , "Coach - item of footwear" .)