Admission made by unknown female tucking into dish (5,3)
I believe the answer is:
entry fee
'admission' is the definition.
'unknown female tucking into dish' is the wordplay.
'unknown' becomes 'y' (algebra).
'female' becomes 'f' (abbreviation).
'tucking into' is an insertion indicator.
'dish' becomes 'entree' (I've seen this before**).
'y'+'f'='yf'
'yf' placed within 'entree' is 'ENTRY FEE'.
'made by' acts as a link.
(Other definitions for entry fee that I've seen before include "Admission charge" , "Teeny ref seeking payment to get in" , "Tyne reef (anag.)" , "Price paid to gain admittance" , "Cost of starting" .)