Courtyard built by Irishman I love? (5)
I believe the answer is:
patio
'courtyard' is the definition.
(a patio is an outdoor space or courtyard)
'irishman i love?' is the wordplay.
'irishman' becomes 'pat'.
'i love?' becomes 'io' (I've seen this in other clues).
'pat'+'io'='PATIO'
'built by' acts as a link.
(Other definitions for patio that I've seen before include "Paved outdoor area" , "Place to sit" , "Garden terrace" , "Where Barbie might be held" , "Paved area outside house" .)