Solve one problem to bear fruit (6)
I believe the answer is:
olives
'bear fruit' is the definition.
'olives' can be an answer for 'fruit'. I'm not certain of the 'bear' bit.
'solve one problem' is the wordplay.
'one' becomes 'i' (Roman numeral).
'problem' is an anagram indicator.
'solve'+'i'='solvei'
'solvei' with letters rearranged gives 'OLIVES'.
'to' acts as a link.
Can you help me to learn more?
(Other definitions for olives that I've seen before include "Small green Mediterranean tree-fruits" , "The fruits are important source of oil" , "Yellowish green fruits" , "Trees grown for their oil-producing fruit" , "Small green stone fruits, nice in cocktails" .)