Adheres to what one said and is available when needed (6,2)
I believe the answer is:
stands by
'adheres to' is the definition.
('stand by' can be a synonym of 'adhere to')
'what one said and is available when needed' is the wordplay.
I cannot really see how this works, but
'one' could be 'an' (an apple is one apple) and 'an' is present in the answer.
'said' could be 't' (I've seen this in other clues) and 't' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for stands by that I've seen before include "fails to intervene" , "gives support" , "Is supportive" , "Is available" , "Is ready" .)