When clear outside, start to lift one blind (9)
I believe the answer is:
oblivious
'blind' is the definition.
(synonyms)
'when clear outside start to lift one' is the wordplay.
'when clear' becomes 'obvious' (similar in meaning. I am not sure about the 'when' bit.).
'outside' indicates putting letters inside.
'start to' says to take the initial letters.
'one' becomes 'I' (Roman numeral).
The initial letter of 'lift' is 'l'.
'l'+'i'='li'
'obvious' placed around 'li' is 'OBLIVIOUS'.
Can you help me to learn more?
(Other definitions for oblivious that I've seen before include "like Lethe?" , "In ignorance" , "Blind (to)" , "totally in the dark?" , "Not noticing" .)