Wood making church gloomy mostly (5)
I believe the answer is:
cedar
'wood' is the definition.
(cedar is a kind of wood)
'church gloomy mostly' is the wordplay.
'church' becomes 'ce' (abbreviation for Church of England).
'gloomy' becomes 'dark' ('dark' can be similar in meaning to 'gloomy').
'mostly' means to remove the last letter.
'dark' with its last letter removed is 'dar'.
'ce'+'dar'='CEDAR'
'making' acts as a link.
(Other definitions for cedar that I've seen before include "Raced around a great hardwood tree" , "Fragrant conifer" , "Tall conifer" , "Leaving body" , "Cypress-like tree" .)