The sort of service for mum? (6)
I believe the answer is:
silent
'for mum?' is the definition.
(to keep mum can informally mean to stay silent)
'the sort of service' is the wordplay.
I cannot really understand how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is located in the answer.
The remaining letters 'silen' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for silent that I've seen before include "Taciturn" , "Unheard" , "Listen (anag.)" , "Lacking sound" , "Mute" .)