Track head of Ealing film studio (5)
I believe the answer is:
pathe
'film studio' is the definition.
(I know that Pathe is a film studio)
'track head of ealing' is the wordplay.
'track' becomes 'path' (synonyms).
'head of' suggests taking the first letters.
The initial letter of 'ealing' is 'e'.
'path'+'e'='PATHE'
(Other definitions for pathe that I've seen before include "Cinema newsreel company" , "Charles -, introduced newsreels to UK" , "Producer of newsreels" .)