Style having fewer frills could be rubbish (10)
I believe the answer is:
balderdash
'be rubbish' is the definition.
(I've seen this before)
'style having fewer frills' is the wordplay.
I cannot quite see how this works, but
'style' could be 'dash' (synonyms) and 'dash' is present in the answer.
The remaining letters 'balder' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'could' is the link.
Can you help me to learn more?
(Other definitions for balderdash that I've seen before include "Piffle" , "Senseless talk" , "Twaddle" , "Rubbish" , "tripe" .)