Bit of food in hospital eaten by boy, going the wrong way (4)
I believe the answer is:
dhal
'bit of food' is the definition.
(lentil-based dish)
'hospital eaten by boy going the wrong way' is the wordplay.
'hospital' becomes 'h' (abbreviation for hospital on maps).
'eaten by' is an insertion indicator.
'boy' becomes 'lad' (informal term for boy).
'going the wrong way' says the letters should be written backwards.
'h' put inside 'lad' is 'lahd'.
'lahd' written backwards gives 'DHAL'.
'in' acts as a link.
(Other definitions for dhal that I've seen before include "Split pulses (in Indian cookery)" , "Pigeon pea" , "Indian dish of dried pulses" , "Pigeon-pea" , "Pakistani veg" .)