Pleased to have flag flying around party (4,2)

'pleased' is the definition.
(if you're glad of something you're pleased by it)

'flag flying around party' is the wordplay.
'flying' is an anagram indicator (letters fly around into new positions).
'around' means one lot of letters goes inside another.
'party' becomes 'do' (do is a kind of party).
'flag' is an anagram of 'glaf'.
'glaf' going around 'do' is 'GLAD OF'.

'to have' is the link.