Without delay, starts to applaud, sing and pray (4)
I believe the answer is:
asap
'without delay' is the definition.
(as soon as possible)
'starts to applaud sing and pray' is the wordplay.
'starts to' suggests taking the first letters.
The initial letters of 'applaud sing and pray' is 'ASAP'.
(Other definitions for asap that I've seen before include "'As quickly as you can, initially (4)'" , "Notation meaning without delay, treat as urgent" , "Notation meaning without delay, fast as you can" , "Common acronym for quick-as-you-can" , "Notation or acronym meaning without avoidable delay" .)