Son's on notice, with head getting grief (7)
I believe the answer is:
sadness
'grief' is the definition.
(I've seen this before)
'son's on notice with head' is the wordplay.
'on' is a charade indicator (letters next to each other).
'notice' becomes 'ad' (short for advert).
'with' says to put letters next to each other.
'head' becomes 'ness' (ness is a headland).
's'+'ad'+'ness'='SADNESS'
'getting' acts as a link.
(Other definitions for sadness that I've seen before include "Melancholy" , "no joy there" , "Misery" , "regret" , "Grief" .)