The basis of bread is hard to grow profusely (8)
I believe the answer is:
flourish
'grow profusely' is the definition.
'flourish' can be an answer for 'grow' (flourishing is a kind of growing). I'm not certain of the 'profusely' bit.
'the basis of bread is hard' is the wordplay.
'the basis of bread' becomes 'flour' (bread is made from flour).
'hard' becomes 'h' (abbreviation used in pencil classifications).
'flour'+'is'+'h'='FLOURISH'
'to' is the link.
Can you help me to learn more?
(Other definitions for flourish that I've seen before include "Fine food is hard to" , "show off" , "Thrive; ornamental passage of music" , "Bloom" , "Grow vigorously and healthily" .)