Fleet circling round provided calm (6)
I believe the answer is:
pacify
'calm' is the definition.
(pacifying is a kind of calming)
'fleet circling round provided' is the wordplay.
I cannot really understand how this works, but
'provided' could be 'if' (eg 'provided it's sunny' means 'if it's sunny') and 'if' is located in the answer.
'fleet' could be 'pacy' (both can mean quick) and 'pacy' is found within the remaining letters.
No letters remain.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for pacify that I've seen before include "Quell the anger of" , "Make calm, appease" , "Bring peace to (a place)" , "Make calm, soothe" , "Quieten" .)