Equatorial river's missing current (7)
I believe the answer is:
topical
'current' is the definition.
(similar in meaning)
'equatorial river's missing' is the wordplay.
'equatorial' becomes 'tropical' (similar in meaning).
'river' becomes 'r' (abbreviation for river).
'missing' suggests deleting specific letters.
'tropical' with 'r' removed is 'TOPICAL'.
(Other definitions for topical that I've seen before include "Of local interest" , "About current events in Capitol" , "currently newsworthy" , "Applied externally" , "Relating to current affairs" .)