Storing bits of pine in a small cask (7)
I believe the answer is:
keeping
'storing bits' is the definition.
'keeping' can be an answer for 'storing' (I've seen this in another clue). I am not sure about the 'bits' bit.
'of pine in a small cask' is the wordplay.
'of' indicates an anagram (the answer comes from or 'of' the letters).
'in' is an insertion indicator.
'a small cask' becomes 'keg' (I've seen this before).
'pine' with letters rearranged gives 'epin'.
'epin' placed within 'keg' is 'KEEPING'.
Can you help me to learn more?
(Other definitions for keeping that I've seen before include "Charge" , "Delaying" , "Maintaining" , "Holding on to" , "Custody" .)