Uniform covered in strong-smelling, phosphorus-free ointment (7)
I believe the answer is:
unguent
'ointment' is the definition.
(synonyms)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for unguent that I've seen before include "application" , "Oily substance" , "Lubricant to tune gun" , "Balm, ointment" , "Lotion" .)