Head, accepting haircut, went inside for food (9)
I believe the answer is:
nutriment
'food' is the definition.
(nutriment is a kind of food)
'head accepting haircut went inside' is the wordplay.
'head' becomes 'nut' (informal term for somebody's head).
'accepting' indicates putting letters inside.
'haircut' becomes 'trim' (I've seen this before**).
'inside' indicates the central letters.
The central letters of 'went' are 'en'.
'trim'+'en'='trimen'
'nut' placed around 'trimen' is 'NUTRIMENT'.
'for' is the link.
(Other definitions for nutriment that I've seen before include "It sustains" , "Nourishing food" , "Material providing food" , "diet" , "Sustenance, nourishment" .)