Was accustomed to function back of beyond (4)
I believe the answer is:
used
'was accustomed' is the definition.
I can't tell whether this defines the answer.
'function back of beyond' is the wordplay.
'function' becomes 'use' (something's use is its function).
'back of' says to take the final letters.
The last letter of 'beyond' is 'd'.
'use'+'d'='USED'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for used that I've seen before include "Exploited group" , "Second-hand; consumed" , "Worn" , "Sued (anag.)" , "Dog-eared" .)