Rigid dry container for gold (4)
I believe the answer is:
taut
'rigid' is the definition.
(I've seen this in another clue)
'dry container for gold' is the wordplay.
'dry' becomes 'tt' (abbreviation for teetotal).
'container for' is an insertion indicator.
'gold' becomes 'au' (Au is the chemical symbol for gold).
'tt' placed around 'au' is 'TAUT'.
(Other definitions for taut that I've seen before include "Tense, stretched tight" , "On the slope" , "Fully stretched" , "Pulled or drawn tight" , "Without slack" .)