Does it sometimes provide the gardener with a knotty problem? (6,4)
I believe the answer is:
string bean
'knotty problem?' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'does it sometimes provide the gardener with a' is the wordplay.
I cannot quite see how this works, but
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is present in the answer.
'a' could be 'an' and 'an' is located in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Another definition for string bean that I've seen is " What may be French or runner".)