Competent, in a position to (4)
I believe the answer is:
able
I believe this clue is a double definition.
'competent' is the first definition.
(similar in meaning)
'in a position to' is the second definition.
(I've seen this before)
(Other definitions for able that I've seen before include "Having the ability to do something" , "Fully competent" , "Skilled" , "Proficient; skilful" , "Practised" .)