Power of second crew (5)
I believe the answer is:
steam
'power' is the definition.
(thesaurus)
'second crew' is the wordplay.
'second' becomes 's' (common abbreviation).
'crew' becomes 'team' (I've seen this before).
's'+'team'='STEAM'
'of' is the link.
(Other definitions for steam that I've seen before include "Like old radio" , "A lot of hot air" , "Hot water suspended in air" , "What powered old engines" , "fume" .)