King had second ranks (5)
I believe the answer is:
rates
'ranks' is the definition.
('rate' can be a synonym of 'rank')
'king had second' is the wordplay.
'king' becomes 'R' (abbreviation for rex, king in Latin).
'had' becomes 'ate' (e.g. I had an ice cream).
'second' becomes 's' (common abbreviation).
'r'+'ate'+'s'='RATES'
(Other definitions for rates that I've seen before include "Esteems, values" , "Property-based source of local revenue" , "Fixed prices" , "Relative speeds and local taxes" , "judges" .)