Uniform on lad good for religious service (8)
I believe the answer is:
evensong
'religious service' is the definition.
(I've seen this before)
'uniform on lad good' is the wordplay.
'uniform' becomes 'even' (I've seen this in another clue).
'on' says to put letters next to each other.
'lad' becomes 'son' (lad can informally mean a young boy).
'good' becomes 'g' (abbreviation).
'even'+'son'+'g'='EVENSONG'
'for' acts as a link.
(Other definitions for evensong that I've seen before include "Anglican service" , "... Prayers" , "Vespers" , "Service of evening prayer in Church of England" , "Religious service" .)