First, say, work on laird (7)
I believe the answer is:
ordinal
'first say' is the definition.
('first' is an ordinal number)
'work on laird' is the wordplay.
'work' indicates an anagram.
'on'+'laird'='onlaird'
'onlaird' is an anagram of 'ORDINAL'.
(Other definitions for ordinal that I've seen before include "First and second, say" , "Type of number" , "First, second, third could be such a numeral" , "The associate of Cardinal" , "RC Church service book" .)