Join the service, perhaps? (4)
I believe the answer is:
pray
'join the service perhaps?' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for pray that I've seen before include "Beseech" , "Call upon in supplication" , "Make supplication (to a god)" , "Commune with God" , "Hope earnestly (for particular outcome)" .)