It helps to make sex tremendously intense (7)
I believe the answer is:
extreme
'intense' is the definition.
(similar in meaning)
'it helps to make sex tremendously' is the wordplay.
'it helps to make' indicates a hidden word (the letters of the answer help to make the clue).
'EXTREME' is hidden in the letters of 'sex tremendously'.
(Other definitions for extreme that I've seen before include "Utmost; excessive" , "Most remote or utmost" , "not near the centre" , "Immoderate" , "Greatest or smallest" .)