Reasonable travel cost announced (4)
I believe the answer is:
fair
'reasonable' is the definition.
(synonyms)
'travel cost announced' is the wordplay.
'travel cost' becomes 'fare' (as in a train fare).
'announced' indicates a 'sounds like' (homophone) clue.
'fare' is a homophone of 'FAIR'.
(Other definitions for fair that I've seen before include "gorgeous" , "Equitable or blond" , "Having light-coloured hair and skin" , "Just; amusement" , "Unbiased; carnival" .)