Clear first of plants I culled ineptly (8)
I believe the answer is:
pellucid
'clear' is the definition.
(similar in meaning)
'first of plants i culled ineptly' is the wordplay.
'first of plants' becomes 'p' (1st letter of 'plants').
'ineptly' is an anagram indicator (an inept spelling).
'i'+'culled'='iculled'
'iculled' is an anagram of 'ellucid'.
'p'+'ellucid'='PELLUCID'
(Other definitions for pellucid that I've seen before include "Very clear, totally transparent" , "Crystal-clear" , "Translucent" , "Translucently clear" , "Absolutely crystal clear" .)