MP needs support entering global alliance: plenty given! (7)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

MP + TEE (support for a golf ball), entering UN (United Nations = global alliance). Umpteen = an unspecified large number = plenty. The “given” helps with the sense of the surface, but doesn’t do anything for the definition. Interestingly, for the surface, we’ve just had an MP (Matt Hancock) announcing he would take on an unpaid role with the UN, but then they withdrew their support; it seems they remembered a rule that a serving MP can’t do that. Awkward.