Imply port swallowed is of a lower standard (8)
I believe the answer is:
inferior
'of a lower standard' is the definition.
(I've seen this before)
'imply port swallowed' is the wordplay.
'imply' becomes 'infer' (I've seen this before).
'port' becomes 'rio' (Rio de Janeiro is a port).
'swallowed' indicates putting letters inside.
'infer' placed around 'rio' is 'INFERIOR'.
'is' acts as a link.
(Other definitions for inferior that I've seen before include "Of poor quality" , "Lower in rank or quality" , "Less important, valuable" , "Substandard, lower in quality" , "Lower in standard or rank" .)