Sailor almost certain daughter's bonkers (6)
I believe the answer is:
absurd
'bonkers' is the definition.
Both the definition and answer are adjectives. Perhaps they are linked in a way I don't understand?
'sailor almost certain daughter's' is the wordplay.
'sailor' becomes 'ab' (abbreviation for able seaman).
'almost' means to remove the last letter (almost the whole word is kept).
'certain' becomes 'sure' (synonyms).
'daughter' becomes 'd' (genealogical abbreviation).
'sure' with its final letter taken off is 'sur'.
'ab'+'sur'+'d'='ABSURD'
Can you help me to learn more?
(Other definitions for absurd that I've seen before include "'Ridiculous, silly (6)'" , "irrational" , "Ridiculous, ludicrous" , "Foolish, quite ridiculous" , "Ridiculous, quite nonsensical" .)