A huge amount of sticky stuff: precious commodity, mostly (6)
I believe the answer is:
googol
'a huge amount' is the definition.
'sticky stuff precious commodity mostly' is the wordplay.
'sticky stuff' becomes 'goo' (I've seen this before).
'precious commodity' becomes 'gold'.
'mostly' means to remove the last letter.
'gold' with its last letter taken off is 'gol'.
'goo'+'gol'='GOOGOL'
'of' is the link.
(Other definitions for googol that I've seen before include "unimaginable figure" , "Vast figure" , "10100" , "Big number" , "Ten to the power of 100" .)