Boatman's one to advance as a paradigm (5)
I believe the answer is:
imago
'a paradigm' is the definition.
(I know that imago is a type of paradigm)
'boatman's one to advance' is the wordplay.
'boatman's' becomes 'I'm' (where the crossword setter is 'Boatman').
'one' becomes 'a' (a thing is one thing).
'to advance' becomes 'go' (to advance is to go forward).
'im'+'a'+'go'='IMAGO'
'as' is the link.
(Other definitions for imago that I've seen before include "Mature insect after metamorphosis" , "Insect at end of life" , "Final stage of insect development" , "Last stage of adult insect" , "Maybe comma" .)