Scream one's stifled at church crush (7)
I believe the answer is:
squelch
'crush' is the definition.
(synonyms)
'scream one's stifled at church' is the wordplay.
'scream' becomes 'squeal'.
'one' becomes 'a'.
'stifled' indicates named letters should be taken away (some letters suppressed or stifled).
'at' means one lot of letters go next to another.
'church' becomes 'ch' (common abbreviation).
'squeal' with 'a' taken out is 'squel'.
'squel'+'ch'='SQUELCH'
(Other definitions for squelch that I've seen before include "Sound of a boot in mud" , "silence" , "Sound of muddy walk" , "Soft sucking sound, when walking through it, of wet mud" , "Noise of walking through wet mud" .)