Gambles about Scrabble tiles holder (in these) (8)
I believe the answer is:
brackets
'these' is the definition.
The definition suggests an adverb but the answer is not.
'gambles about scrabble tiles holder' is the wordplay.
'gambles' becomes 'bets' (bet is a kind of gamble).
'about' means one lot of letters goes inside another.
'scrabble tiles holder' becomes 'rack' (I've seen this in another clue).
'bets' enclosing 'rack' is 'BRACKETS'.
'in' is the link.
Can you help me to learn more?
(Other definitions for brackets that I've seen before include "eight here in these" , "Projecting supports, for a shelf say" .)