Free school meal tiny? Rashford's first to get involved (13)
I believe the answer is:
complimentary
'free' is the definition.
(synonyms)
'school meal tiny? rashford's first to get involved' is the wordplay.
'school' becomes 'comp' (short for comprehensive school).
'rashford's first' becomes 'r' (1st letter of 'rashford').
'to get involved' indicates anagramming the letters.
'meal'+'tiny'+'r'='mealtinyr'
'mealtinyr' anagrammed gives 'limentary'.
'comp'+'limentary'='COMPLIMENTARY'
(Other definitions for complimentary that I've seen before include "Free (ticket); praising" , "Expressing approval - not to be paid for" , "Given free" , "Flattering" , "Clammy pointer (anag) - costing nothing" .)