Lacking capital, one paying for room and board (5)
I believe the answer is:
enter
'board' is the definition.
(I've seen this in another clue)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for enter that I've seen before include "Register (as a competitor)" , "Inscribe" , "Go/come in" , "Fruit drink" , "Move into" .)