Whole tin smashed, giant flipped (8)
I believe the answer is:
integral
'whole' is the definition.
(similar in meaning)
'tin smashed giant flipped' is the wordplay.
'smashed' is an anagram indicator.
'giant' becomes 'large' (similar in meaning).
'flipped' says the letters should be written in reverse.
'large' written backwards gives 'egral'.
'tin' anagrammed gives 'int'.
'int'+'egral'='INTEGRAL'
(Other definitions for integral that I've seen before include "United" , "Full" , "using no fractions" , "Altering (anag)" , "Fundamental; function" .)