Pressure to charge at gunner ordering offensive (9)
I believe the answer is:
repugnant
'offensive' is the definition.
(similar in meaning)
'pressure to charge at gunner ordering' is the wordplay.
'pressure' becomes 'p' (scientific abbreviation).
'to charge' is an insertion indicator (charge can mean to fill).
'ordering' indicates an anagram.
'at'+'gunner'='atgunner'
'atgunner' with letters rearranged gives 'reugnant'.
'p' placed into 'reugnant' is 'REPUGNANT'.
(Other definitions for repugnant that I've seen before include "Very unwelcome" , "vile" , "Extremely distasteful" , "revolting" , "Abhorrent" .)