Attempting very odd wordplay, beginners swear (4)
I believe the answer is:
avow
'swear' is the definition.
(I know that swear can be written as avow)
'attempting very odd wordplay beginners' is the wordplay.
'beginners' suggests taking the first letters.
The initial letters of 'attempting very odd wordplay' is 'AVOW'.
(Other definitions for avow that I've seen before include "State openly" , "Solemnly declare" , "acknowledge" , "Strongly maintain" , "Declare - admit" .)