Perks from head of firm being free isn't unusual (6,8)
I believe the answer is:
fringe benefits
'perks' is the definition.
('fringe benefit' can be a synonym of 'perk')
'head of firm being free isn't unusual' is the wordplay.
'head of' says to take the initial letters.
'unusual' is an anagram indicator.
The initial letter of 'firm' is 'f'.
'being'+'free'+'isnt'='beingfreeisnt'
'beingfreeisnt' with letters rearranged gives 'ringebenefits'.
'f'+'ringebenefits'='FRINGE BENEFITS'
'from' acts as a link.
(Other definitions for fringe benefits that I've seen before include "Perks" , "offered to hairdressers, quite possibly?" .)