Is this gud for acne? Clindamycin phosphate BP equivalent to clindamycin nicotinamide i.P in aloe allantion base with ethyl lactate, its a gel

Yes. Do not use it as monotherapy -- always use benzoyl peroxide or some other topical agent (a retinoic acid derivative) in addition. The retinoic acid derivative might be the better choice since you indicate numerous blackheads.