Weak film, stupid and extremely silly (6)
I believe the answer is:
flimsy
'weak' is the definition.
(similar in meaning)
'film stupid and extremely silly' is the wordplay.
'stupid' indicates anagramming the letters (in a stupid order).
'and' means one lot of letters go next to another.
'extremely' means to remove the middle letters.
'silly' with its middle taken out is 'sy'.
'film' is an anagram of 'flim'.
'flim'+'sy'='FLIMSY'
(Other definitions for flimsy that I've seen before include "Lacking strength and solidity" , "Insubstantial, light and thin" , "Light and thin, fragile" , "Light and thin, easily torn or broken" , "Weak, insubstantial" .)