Pardon sailor only round start of voyage (7)
I believe the answer is:
absolve
'pardon' is the definition.
(thesaurus)
'sailor only round start of voyage' is the wordplay.
'sailor' becomes 'ab' (abbreviation for able seaman).
'only' becomes 'sole' ('sole' can be a synonym of 'only').
'round' indicates putting letters inside.
'start of' indicates taking the first letters.
The first letter of 'voyage' is 'v'.
'sole' enclosing 'v' is 'solve'.
'ab'+'solve'='ABSOLVE'
(Other definitions for absolve that I've seen before include "Declare (someone) blameless" , "Declare (someone) free of guilt" , "Exonerate" , "Grant pardon for" , "Set free from guilt" .)