Public house, very large, repeatedly holding RU match needs this (10)
I believe the answer is:
phosphorus
'match needs this' is the definition.
The definition suggests a singular noun which matches the answer.
'public house very large repeatedly holding ru' is the wordplay.
'public house' becomes 'ph' (abbreviation).
'very large' becomes 'os' (abbreviation for oversize).
'repeatedly' indicates the doubling of some letters.
'holding' indicates putting letters inside.
'ph'+'os'='phos'
'phos' duplicated is 'phosphos'.
'phosphos' placed around 'ru' is 'PHOSPHORUS'.
Can you help me to learn more?
(Other definitions for phosphorus that I've seen before include "Element producing sort of light" , "Flammable illuminating material" , "It lights" , "Element, symbol P" , "Combustible element" .)