Dropping behind, hit good smash - swap ends for service (4,4)
I believe the answer is:
high mass
'for service' is the definition.
(I've seen this before)
'dropping behind hit good smash swap' is the wordplay.
'dropping behind' means to remove the last letter (the word's back or behind is dropped).
'good' becomes 'g' (abbreviation).
'swap' is an anagram indicator (I've seen 'swaps' mean this).
'hit' with its last letter removed is 'hi'.
'smash' with letters rearranged gives 'hmass'.
'hi'+'g'+'hmass'='HIGH MASS'
'ends' acts as a link.
I am not very happy about this link. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for high mass that I've seen before include "Church service celebrated with music, incense etc" , "full service" .)