What to pay to get a single school meal? (5,4)
I believe the answer is:
train fare
'what to pay to get a single' is the definition.
(single train fare)
'school meal?' is the wordplay.
'school' becomes 'train' (training is a kind of schooling).
'meal?' becomes 'fare' (I've seen this before).
'train'+'fare'='TRAIN FARE'
(Other definitions for train fare that I've seen before include "Perhaps commute cost" , "the cost of going" .)