Noise in church unpleasant, not half (4)
I believe the answer is:
chug
'noise' is the definition.
(I know that chug is a type of noise)
'church unpleasant not half' is the wordplay.
'church' becomes 'ch' (common abbreviation).
'unpleasant' becomes 'ugly' (I've seen this in another clue).
'not half' means to take half the letters.
'ugly' with half the letters taken is 'ug'.
'ch'+'ug'='CHUG'
'in' is the link.
(Other definitions for chug that I've seen before include "drink" , "Noise of a slow engine" , "Dull noise made by an engine" .)