Head of studio with hard mat making shoulder gesture (5)
I believe the answer is:
shrug
'shoulder gesture' is the definition.
(I've seen this before)
'head of studio with hard mat' is the wordplay.
'head of' indicates taking the first letters.
'with' says to put letters next to each other.
'hard' becomes 'h' (abbreviation used in pencil classifications).
'mat' becomes 'rug' (floor covering).
The initial letter of 'studio' is 's'.
's'+'h'+'rug'='SHRUG'
'making' acts as a link.
(Other definitions for shrug that I've seen before include "Raise one's shoulders" , "Uncaring gesture" , "Shoulder movement to indicate indifference" , "Sign of indifference" , "Expressive movement of shoulders" .)