Think about getting proficient, becoming hugely important (12)
I believe the answer is:
considerable
'hugely important' is the definition.
(considerable can mean very important or notable)
'think about getting proficient' is the wordplay.
'think about' becomes 'consider ' (to consider something is to think about it).
'getting' is a charade indicator (letters next to each other).
'proficient' becomes 'able' (able can mean capable or proficient).
'consider'+'able'='CONSIDERABLE'
'becoming' acts as a link.
(Other definitions for considerable that I've seen before include "Significant" , "Relatively large" , "Notably large" , "A lot (of) - worthy of respect" , "Fairly large or numerous" .)