Crew ultimately provides muscle (5)
I believe the answer is:
squad
'crew ultimately' is the definition.
'squad' can be an answer for 'crew' (Another word for crew). I am not sure about the 'ultimately' bit.
'provides muscle' is the wordplay.
'provides' becomes 's' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'muscle' becomes 'quad' (quad is a kind of muscle).
's'+'quad'='SQUAD'
(Other definitions for squad that I've seen before include "Smallest army unit" , "Body of soldiers" , "Group (of soldiers, players etc)" , "Small military unit" , "Smallest military formation" .)