Beat gold in the open air (7)
I believe the answer is:
outdoor
'in the open air' is the definition.
(I've seen this before)
'beat gold' is the wordplay.
'beat' becomes 'outdo' (outdoing is a kind of beating).
'gold' becomes 'or' ('or' is the heraldic name for gold).
'outdo'+'or'='OUTDOOR'
(Other definitions for outdoor that I've seen before include "Open-air" , "not under cover" , "External" , "in the garden, say" , "healthy pursuits" .)