Correct height for an oil platform (5)
I believe the answer is:
right
'correct' is the definition.
(synonyms)
'height for an oil platform' is the wordplay.
'height' becomes 'ht' (abbreviation).
'for' means one lot of letters go next to another (I've seen this in other clues).
'an oil platform' becomes 'rig' (I've seen this before).
'ht' put after 'rig' is 'RIGHT'.
(Other definitions for right that I've seen before include "Due" , "Morally defensible" , "Sound" , "Privy Councillors are so honourable" , "Morally good; rectify" .)