It's many years since pine's been given a try (4,3)
I believe the answer is:
long ago
'it's many years' is the definition.
I can't judge whether this definition defines the answer.
'since pine's been given a try' is the wordplay.
I cannot quite understand how this works, but
'since' could be 'ago' (I've seen this before) and 'ago' is found in the answer.
'pine' could be 'long' (to pine for something is to long for it) and 'long' is present in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for long ago that I've seen before include "In the far past" , "in the 26 [PAST]" , "Very far back in time" , "In times gone by" , "way back" .)