What about phosphorus: nearly green for a short time (9)
I believe the answer is:
ephemeral
'short time' is the definition.
'ephemeral' can be an answer for 'short' (thesaurus). I'm unsure of the 'time' bit.
'what about phosphorus nearly green' is the wordplay.
'what' becomes 'eh' (sound used to ask 'what?' or 'pardon?').
'about' means one lot of letters goes inside another.
'phosphorus' becomes 'P' (P is the chemical symbol for phosphorus).
'nearly' means to remove the last letter.
'green' becomes 'emerald' (emerald is a shade of green).
'eh' going around 'p' is 'eph'.
'emerald' with its final letter removed is 'emeral'.
'eph'+'emeral'='EPHEMERAL'
'for a' is the link.
Can you help me to learn more?
(Other definitions for ephemeral that I've seen before include "Transitory" , "Transient, fleeting" , "Having only brief existence" , "Fugitive" , "short term gain" .)