Synonyms for Slap-up:

n.

frugal, sit down, light, hearty, set, satisfying, alfresco, heavy, celebratory. slap-up (noun)
good, peachy, great, corking, bully, cracking, swell, nifty, keen, bang up, not bad, neat, dandy, smashing, groovy.

Other synonyms:

sit down, celebratory, satisfying, frugal. alfresco, hearty. heavy, light. set. bang-up
bang up.
Other relevant words:
celebratory, heavy, alfresco, frugal, set, satisfying.