Corn provides about right profit (5)
I believe the answer is:
grain
'corn' is the definition.
(I've seen this before)
'about right profit' is the wordplay.
'about' indicates putting letters inside.
'right' becomes 'r' (common abbreviation).
'profit' becomes 'gain' (synonyms).
'r' inserted within 'gain' is 'GRAIN'.
'provides' acts as a link.
(Other definitions for grain that I've seen before include "Eg, wheat" , "Small particle - weight" , "Cereal crops" , "Cereal seed" , "Cereal as food" .)