Airline occasionally kept charge back on board for hot drink (4,3)
I believe the answer is:
beef tea
'hot drink' is the definition.
(I've seen this before)
'airline occasionally kept charge back on board' is the wordplay.
'airline' becomes 'ba' (British Airways).
'occasionally' indicates alternate letters.
'charge' becomes 'fee' (fee is a kind of charge**).
'back' says the letters should be written in reverse.
'on board' indicates putting letters inside.
The alternate letters of 'kept' are 'et'.
'et'+'fee'='etfee'
'etfee' back-to-front is 'eefte'.
'ba' going around 'eefte' is 'BEEF TEA'.
'for' is the link.
(Other definitions for beef tea that I've seen before include "Meat solution for invalids" , "Meaty drink" , "Savoury drink" , "Drink made from boiled meat" , "Hot drink made with meat" .)