In addition to sea wall getting fixed, welcoming second (2,4,2)
I believe the answer is:
as well as
'in addition to' is the definition.
(I've seen this before)
'sea wall getting fixed welcoming second' is the wordplay.
'getting fixed' indicates anagramming the letters.
'welcoming' is an insertion indicator (in sense of 'inviting in').
'second' becomes 's' (common abbreviation).
'sea'+'wall'='seawall'
'seawall' anagrammed gives 'awellas'.
'awellas' enclosing 's' is 'AS WELL AS'.
(Other definitions for as well as that I've seen before include "In addition to, also" , "this can be expected when in reasonable health" , "Supplementing" , "In addition to (2, 4, 2)" , "No less than" .)